COSEWIC Assessment and Status Report on the White Shark Carcharodon carcharias Atlantic population Pacific population in Canada ATLANTIC POPULATION – ENDANGERED PACIFIC POPULATION – DATA DEFICIENT 2006 COSEWIC COSEPAC COMMITTEE ON THE STATUS OF COMITÉ SUR LA SITUATION ENDANGERED WILDLIFE DES ESPÈCES EN PÉRIL IN CANADA AU CANADA COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows: COSEWIC 2006. COSEWIC assessment and status report on the White Shark Carcharodon carcharias (Atlantic and Pacific populations) in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 31 pp. (www.sararegistry.gc.ca/status/status_e.cfm). Production note: COSEWIC would like to acknowledge R. Aidan Martin and Scott Wallace for writing the status report on the white shark, Carcharodon carcharias, (Atlantic and Pacific populations) in Canada, prepared under contract with Environment Canada. The report was overseen and edited by Mart Gross and Paul Bentzen (Co-chairs, COSEWIC Marine Fishes Species Specialist Subcommittee). For additional copies contact: COSEWIC Secretariat c/o Canadian Wildlife Service Environment Canada Ottawa, ON K1A 0H3 Tel.: (819) 997-4991 / (819) 953-3215 Fax: (819) 994-3684 E-mail: COSEWIC/[email protected] http://www.cosewic.gc.ca Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur le requin blanc (Carcharodon carcharias) populations de l’Atlantique et du Pacifique au Canada. Cover illustration: White Shark — Provided by R. Aidan Martin. ©Her Majesty the Queen in Right of Canada 2006 Catalogue No. CW69-14/507-2006E-PDF ISBN 0-662-43322-X Recycled paper COSEWIC Assessment Summary Assessment Summary – April 2006 Common name White shark – Atlantic population Scientific name Carcharodon carcharias Status Endangered Reason for designation The species is globally distributed in sub-tropical and temperate waters, but absent from cold polar waters; hence Atlantic and Pacific populations in Canada are isolated from each other and are considered separate designatable units. This very large apex predator is rare in most parts of its range, but particularly so in Canadian waters, which represent the northern fringe of its distribution. There are only 32 records over 132 years for Atlantic Canada. No abundance trend information is available for Atlantic Canada. Numbers have been estimated to have declined by about 80% over 14 years (less than one generation) in areas of the Northwest Atlantic Ocean outside of Canadian waters. The species is highly mobile, and individuals in Atlantic Canada are likely seasonal migrants belonging to a widespread Northwest Atlantic population; hence the status of the Atlantic Canadian population is considered to be the same as that of the broader population. Additional considerations include the long generation time (~23 years) and low reproductive rates (estimated gestation is 14 months and average fecundity is 7 live-born young) of this species, which limit its ability to withstand losses from increase in mortality rates. Bycatch in the pelagic long line fishery is considered to be the primary cause of increased mortality. Occurrence Atlantic Ocean Status history Designated Endangered in April 2006. Assessment based on a new status report. Assessment Summary – April 2006 Common name White shark – Pacific population Scientific name Carcharodon carcharias Status Data Deficient Reason for designation The species is globally distributed in sub-tropical and temperate waters, but absent from cold polar waters; hence Atlantic and Pacific populations in Canada are isolated from each other and are considered separate designatable units. This very large apex predator is rare in most parts of its range, but particularly so in Canadian waters, which represent the northern fringe of its distribution. There are only 14 records over 43 years for the Pacific coast of Canada. No abundance trend information is available for Pacific Canadian waters, or for adjacent waters in the United States that would permit a status designation. Occurrence Pacific Ocean Status history Species considered in April 2006 and placed in the Data Deficient category. Assessment based on a new status report. iii COSEWIC Executive Summary White Shark Carcharodon carcharias Species information The (great) white shark (Carcharodon carcharias (Linnaeus, 1758)) is the only living species of this genus. In French it is called ‘grand requin blanc’. It is recognizable in the field by its conspicuously black iris and a sharp contrast between dorsal and ventral colouration changing from dark (grey or black) to white. Genetic evidence combined with satellite tracking information clearly shows that this species is wide- ranging. Gene flow between Atlantic and Pacific populations is likely restricted but population structure between hemispheres and ocean basins has not been investigated. There is no known genetic structure in Canadian populations. For the purpose of this report, Canada’s Atlantic and Pacific populations are treated as two separate designatable units. Distribution The white shark is widely distributed in sub-polar to tropical seas of both hemispheres, from 60°N to 60°S, but it is most frequently observed and captured in inshore temperate waters over the continental shelves of the western North Atlantic, Mediterranean Sea, southern Africa, southern Australia, New Zealand, and the eastern North Pacific. Worldwide, this species is rare but does occur with some predictability in certain areas. On both the Atlantic and Pacific coast of Canada, white sharks appear to occur sporadically, known from only 46 confirmed or probable records since 1874. White shark records from Pacific Canada consist almost exclusively of strandings on the leeward shores of the Queen Charlotte Islands (Haida Gwaii) during late autumn and early winter months. Off Atlantic Canada, the white shark has been recorded from the Northeast Newfoundland Shelf, the Strait of Belle Isle, the St. Pierre Bank, Sable Island Bank, the Forchu Misaine Bank, in St. Margaret’s Bay, off Cape La Have, in Passamaquoddy Bay, in the Bay of Fundy, in the Northumberland Strait, and in the Laurentian Channel as far inland as the Portneuf River Estuary. Habitat The white shark occurs in both inshore and offshore waters, from the intertidal to the upper continental slope and mesopelagic zone. Known bathymetric range is from iv just below the surface to just above the bottom down to a depth of at least 1,280 m. It occurs in the breakers off sandy beaches, off rocky shores, and readily enters enclosed bays, lagoons, harbours, and estuaries, but does not penetrate brackish or fresh waters to any extent. Biology Reproductive mode is ovoviviparous. Gestation period is unknown, but may be about 14 months, inferred from the estimated gestation of the closely related shortfin mako. Litter size varies from 2 to 10 and possibly to 17 with an average of 7, with fecundity increasing with size of the female. Length at birth is assumed to be between 109 and 165 cm, with known length of the smallest free-swimming neonates 109 to 129 cm. Possible white shark pupping areas on the west and east coasts of North America include off southern California and the Mid-Atlantic Bight, respectively. Length of reproductive cycle in the white shark is unknown, but may be more than three years as post-partum females may take a year or more off between pregnancies to rebuild energy stores. Maximum lifetime reproductive output of a female white shark has been estimated to be 45 pups with pup survival considered to be low. Age and size at maturity in white sharks varies regionally. Males reach sexual maturity at an age of 8 to 10 years and a length of 3.5 to 4.1 m while females reach maturity at an age of 12 to 18 years and a length of 4 to 5 m. Longevity in this species is estimated to be 23-60 years. Generation time has been estimated at 23 years and natural mortality at 0.077 year–1 and 0.125 year–1. Intrinsic rate of population increase is estimated at 0.04-0.056. White sharks are an apex predator with a wide prey base feeding primarily on teleosts, elasmobranchs, and marine mammals, as well as cephalopods, other molluscs, decapods, marine birds, and reptiles. Biological information from Canadian waters is limited. Population sizes and trends There are no estimates of population size in Canadian waters or elsewhere in the world. The species is apparently rare in Canada with only 32 records in the Atlantic since 1874 (and only one in the last decade) and only 14 records since 1961 in the Pacific. Given the low encounter rate in commercial and recreational fisheries in Canada, abundance in Canada has likely always been much lower than in adjacent southern U.S. waters. White shark population trend information is unknown in North American waters. However, there are several locations throughout the world with documented declines in population. v Limiting factors and threats Humans are the most significant predators of white sharks, taking them as sport fish, commercial bycatch, and for international trade of their valuable body parts. In the Northwest Atlantic, white sharks are taken as bycatch by pelagic longlining operations. In Atlantic Canada there are only two records of white sharks captured in fishing gear since 1990. In Pacific Canada, there are no confirmed records of white sharks caught by fishing activities. Several stranded white sharks on the Queen Charlotte Islands had markings that may have resulted from fishing gear. The white shark’s tendency to investigate boats and other floating objects often brings them to the surface, where they can be easily hooked, shot, or harpooned. Special significance of the species The white shark is the quintessential shark species due to its large size, predatory nature and reputation for occasionally attacking humans. The celebrated cultural status of the white shark makes its jaws and teeth particularly sought-after as curios and its fins for Asian delicacies and traditional medicines.